The
paper describes a study of canal and supplemental ground water used by 544
farmers for wheat growing in the Rechna Doab catchment of Pakistan. The main
objective was to assess the on-farm financial gains through alternate modes of
irrigation and comparing them with conjunctive water use. For econometric
analysis, a linear relationship between the wheat production and different
determinant variables was assumed.

The
results highlighted the problem of increased use of tubewell water in the saline
groundwater zones that had resulted in the deterioration of the groundwater
quality and led to the problem of permanent upconing of saline groundwater.
Conjunctive water management increased the farm income by about Rs. 1000 and
5000 per hectare compared to only using the canal and tubewell water,
respectively The results of
financial analysis show that the net gains were 30 percent higher on the farms
using conjunctive water management as compared to the farms using only tubewell
irrigation.

Conjunctive
water management refers to the use of multiple water resources (surface water
and groundwater in this case) within a basin such that adequate water of
acceptable quality is made available at the farm, in a timely manner for
irrigation. The international literature is filled with the studies on
conjunctive water management and its impact on crop productivity and related
issues [Gangwar and Toorn (1987); Bredehoeft and Young (1983); Gorelick (1988);
Lingen (1988); O’Mara (1988); Shah (1988); Brewer and Sharma (2000); Datta and
Dayal (2000); Raju and Brewer (2000) and Chaudhary (2003)].

In
Pakistan, the literature review shows that all of the previous studies conducted
in the arena of water management reported the management problems leading to the
inefficiencies in irrigation application and reduction in crop productivity, [Kijne
and Velde (1991), Mustafa (1991), Siddiq (1994) and Prathaper et
al. (1994)]. Few of the studies took into consideration the impact of
waterlogging and salinity on productivity at farm level [Prathaper et
al. (1997), Meyer et al. (1996),
O’Connell and Khan (1999), and Sakkhati and Chawala (2002)]. None of these
studies have taken into consideration the alternate modes of irrigation and
farmer returns under conjunctive water management in Pakistan. This paper
focuses on these issues and presents results from the Rechna Doab.

The
Rechna Doab (area between Ravi and Chenab
rivers) has a gross area of 2.98 million hectare (Mha), of which 2.319 Mha is
the Gross Command Area (Figure 1).In
the Rechna Doab, three types of
irrigation sources are commonly used on farms i.e. canal irrigation, tubewell
irrigation and the combination of both. Irrigated
agriculture started in the Rechna Doab in 1892 via the Lower Chenab Canal. The
designed cropping intensity of the irrigation system was pitched low, in the
order of 60-70 percent at the start, but now the cropping intensity is more than
120 percent, indicating the increased water demand. This demand is being met
through more than 180,000 tubewells in the fresh groundwater areas of the Rechna
Doab.

The
soils are tertiary in nature and have recent alluvial deposits that consist of
fine to very fine sand and silt. Soils are southwesterly sloped and the slope is
0.38 meter/kilometer (m/Km) and 0.29 m/Km in the upper part and the lower part,
respectively. Surface salinity is found in patches covering more than 20 percent
of the cultivated area in the Rechna Doab (1.17 Mha).

The
meaning of conjunctive water management and its scope, practices and standards
vary a great deal depending on the scarcity and quality of water in the Rechna
Doab.This
paper attempts to analyze the impact of alternate water management practices on
wheat crop production in the Rechna Doab.

Data Source

The
study was conducted in the 26 irrigation subdivisions of the Rechna Doab.
Primary and secondary data sets have been used to carry out the present
analysis. The primary data set comprised survey data of 543 sample farms. The
sample areas were identified through the use of spatial models. These sample
sites were located in eight districts (Sialkot, Gujranwala, Sheikhupura,
Hafizabad, Faisalabad, T.T. Singh, Jhang and part of the Kabirwala sub-district
of the Khanewal District). The primary data were collected on a well-designed
pre-tested questionnaire from farms (using canal supplies, groundwater, and
combination of both for irrigation) located in 181 different sampling sites. The
secondary data were collected from the Irrigation Department, Salinity
Monitoring Organization (SMO) and Economic Survey of Pakistan (GOP 2002).

Specification of the Model

To
estimate the empirical relationship between wheat production and different
determinant variables, a multiplicative relationship was assumed and the
econometric criteria suggested by Fuss, McFadden and Mundlak (1978), Madala
(1988) and Ramunathan (1992) were used. Based on the adjusted R2
values, a linear model was the best match to test the relationship between wheat
yield input applications, irrigation intensity, quality of water, farm size,
farmer’s experience, formal education and the incidence of salinity, sodicity
and waterlogging on the farm. The effects of different irrigation sources i.e.
Canal, Tubewell and Conjunctive Use (use from C+T), was estimated by using Dummy
variables in the equation. The dependent and independent variables, which are
included in the models, are defined in the following:

According
to Equation 1, if the values of the coefficients (B1- B9)
are positive it shows that investment on seed, fertilizer and irrigation would
increase the production of wheat. The positive values of the coefficients (B10- B12) reflects that the age, experience in farming,
formal education have a direct relationship with wheat production. Negative
values of the coefficients (B13-
B16) show that the incidence of salinity, sodicity, waterlogging
and incidence of culturable waste area on a farm has negative impact on wheat
productivity. The value and the sign of the coefficients (B17-B18)
reflect the impact of tubewell water quality and its age on the wheat
productivity.

In
the Rechna Doab, the farmers exploit groundwater to supplement canal water
supplies. The quality of the groundwater differs spatially. The literature shows
that groundwater of good quality is found in the upper parts of the Doab and in
a 24 to 48 Kilometer wide belt along the flood plains of the Chenab and Ravi
rivers. Highly saline groundwater is found in the lower and central parts of the
Doab.

The
Upper Rechna contains fresh water of 500 parts per million (ppm), but in the
central and lower portions, groundwater salinity concentration varies from 3,000
to 18,000 ppm. In the central and lower parts of the Doab, majority of the
tubewells are pumping marginal to poor quality groundwater, especially at the
tail ends of the canal irrigation system. Table 1 provides figures pertaining to
the farmers’ perception about the quality of irrigation water in the Rechna
Doab.

Out
of the 535 wheat-growing farms, about 47 percent farmers (majority of which is
located in the Upper Rechna Doab) perceived the groundwater quality at their
farms to be good while at about 38 percent of the sample farms located in the
central and lower part of Rechna Doab, the farmers responded that the
groundwater at their farm was saline and was not fit for irrigation.

About
eight percent of the farmers were not aware of the groundwater quality because
they either have just installed the tubewell on the farms or they had taken the
land on lease for the first year. About seven percent of the farmers believed
that they had the marginal quality groundwater, which they were using by mixing
canal water for irrigation purposes.

Table 1. Farmer’s perceptions
about the quality of irrigation water in the Rechna Doab

Farm
Size

Good

Saline

Marginal

Not
Known

All
Categories

Small

39

24

1

6

70

Medium

79

80

11

31

201

Large

135

97

24

8

264

Total

253

201

36

45

535

(47)

(38)

(7)

(8)

(100)

Note: The figures in
parenthesis are percentages.

Out
of total sample farms, about 93 percent farms were using groundwater through
tubewells on their farms (Table 2). About 29 percent of farms were using
tubewell water as the only source of irrigation supplies and about 59 percent of
the total sample farms were using tubewell water to supplement their canal water
supplies. It was observed that it was common in the whole sample farm area that
the farmers have never had a laboratory test for their tubewell water quality.
Thus, it is likely that they might be applying the poor quality tubewell water
to their fields. This would result in problems of salinity or sodicity in their
fields and increased area under secondary salinization.

The
impression one gets by examining these gross numbers is that the farmers are
heavily dependent upon tubewell irrigation to bring more area under cultivation.
The tubewells at the middle and the tail ends of the irrigation network are
pumping poor quality groundwater which may be unfit for irrigation. The
prevailing rate of installation and use of tubewell water may cause problems
relating to the over-exploitation of fresh groundwater reservoir and salt
imbalance buildup of salinity/sodicity. This may result in an increase in
unproductive land, extra costs for groundwater quality improvement and salinized
soil reclamation, and permanent up-coning of saline groundwater.

Table
2. Farmers’ mode of irrigation in the Rechna Doab

Farm
category

Canal

Private
Tubewell

Canal +

Drain

Canal
+ Public T/w

Drain+
Pvt. T/w

All
Categories

Tubewell

Small

7

30

27

1

1

4

70

Medium

16

60

104

2

7

12

201

Large

8

63

169

1

9

14

264

Total

31

153

300

4

17

30

535

(6)

(29)

(56)

(1)

(3)

(6)

(100)

Note:
The figures in parenthesis are percentages.

The
resource use pattern of wheat and output under different types of water
management conditions is presented in Table 3. The expenditure on seed and
fertilizer accounted for about 35 percent of the total cost for wheat
production. The farms using only canal or tubewell water invested four percent
and eight percent less on seed, respectively, to produce wheat as compared to
the farmers using canal and tubewell water conjunctively. Similarly the farms in
the first two categories invested 13 percent and 7 percent less on fertilizer,
respectively to produce wheat as compared to the farmers using canal and
tubewell water conjunctively.

Table 3 shows that land preparation accounts for
about 19 percent of the total cost of wheat production. The farmers using only
canal or tubewell water invested 11 percent and 9 percent less on land
preparation, respectively, to produce wheat as compared to the farmers using
canal and tubewell water conjunctively. The table also reveals that aggregate
resource use per hectare on wheat was about 10 and nine percent lower on farms
using the only canal or only tubewell irrigation, respectively as compared the
farms using both these sources conjunctively. The wheat crop yields estimates
show that it was eight percent and 21 percent higher on the farms using
conjunctive water management as compared to the farms using only canal
irrigation or only tubewell irrigation, respectively. The estimates show that
the net income was 30 percent higher on the farms using conjunctive water
management as compared to the farms using only tubewell irrigation.

Table
3. Input use and output for wheat under different irrigation practices
in the Rechna Doab (Rs./Ha)

Inputs
and Outputs

Source of
Irrigation

Canal

Tubewell

Canal+
Tubewell

Seed

899

867

940

Fertilizer

2810

3004

3222

Labor

362

484

598

Land
preparation

2053

2117

2320

Farm
yard manure

655

438

592

Irrigation

309

510

610

Harvesting
Threshing

3851

3579

3858

Total
cost

10941

10999

12139

Yield
(Kg/Ha)

3465

3337

3773

Gross
income

26516

22672

28746

Net
income

15575

11673

16607

Table
4 shows the results of the estimated regression equation relating wheat
production with the determinant variables. A linear function was selected for
explaining the effect of investment on seed, fertilizer and irrigation inputs
along with the other determinant variables on wheat productivity under different
irrigation practices in the Rechna Doab. The value of adjusted R2 was
0.61.

The
coefficient for X1, X3, X5, X6, X7, X13, X17 and X18 came out to be
statistically significant and had the expected signs.The coefficient for X1 is positive and statistically
significant at 99 percent level of confidence showing that the investment in
better quality wheat seed on the farms practicing conjunctive water management
would increase the productivity of the wheat crop. The coefficient for X2 is
also significant at 90 percent level of confidence and reveals that the
investment on better quality seed would also increase the productivity of wheat
on the farms under canal irrigation.

However,
the dummy variable X3 for investment on seed under tubewell irrigation was non
significant showing no impact on the productivity by investing more on better
quality seed on the farms using tubewells as a source of irrigation. The
coefficient X4 for investment on fertilizer on farms practicing conjunctive use
of water is also statistically significant at a 99 percent level of confidence
and depicts that investment in fertilizer would help in increasing the wheat
yields on these farms. This might be due to more reliability and timely supply
of tubewell water along with the better quality canal water, which moderates the
quality of tubewell water with the conjunctive water management practices.

Unlike
X4 the coefficient for the dummy variable X5 depicts that fertilizer use on
canal-irrigated farms was non-significant showing that the investment on
fertilizer in the canal irrigated areas have no significant impact on wheat
productivity. This may be due to shortage of canal water on these farms, which
results in having no significant impact on wheat crop production. The
coefficient for the dummy variable X6 is negative and statistically significant
at 99 percent level of confidence. It shows that investment in fertilizer may
reduce wheat productivity on the farms that are only using tubewell water for
irrigation.

Table 4.Regression results
relating the wheat production with the determinant factors in the Rechna Doab

This
may be true on the farms located in the areas, which fall in the saline and
brackish groundwater zones. Regarding the coefficients for X7, X8 and X9, only
X8 is statistically significant at 95 percent level of confidence and has a
positive value showing that canal irrigation use has a direct relationship with
the wheat yield.

The
coefficients for X13, X17 and X18 are negative and statistically significant at
95 percent level of confidence. These show that increase in salinity and the age
of the tubewell would reduce wheat productivity. This once again highlights the
problem of increased use of tubewell water in saline zones, which results in the
deterioration of groundwater quality. This problem needs to be addressed at the
policy level by regulating groundwater exploitation by some legal and
institutional framework.

In
this paper, the farmer's mode of irrigation on their farms and their perception
about the quality of water in the Rechna Doab is presented. The study shows that
about 93 percent of the farms were using groundwater in the Rechna Doab. Among
these users about 47 percent were exploiting saline and marginal aquifers. These
farmers were also facing the major threat of salinity on their farms. They
needed to be educated about the conjunctive use of irrigation water to minimize
the effect of salinity on their farms.

The
above results are stark evidence of on-farm gains due to the conjunctive use of
canal and tubewell water. These gains call for more efficient conjunctive water
use on farms. The economic study showed that potential farm benefits could be 30
percent higher in case of wheat provided judicious use of canal and tubewell
irrigation were applied on the farms. The regression results show that low
quality groundwater hampers wheat productivity on the farms. Besides appropriate
government interventions, required to revert the process of land degradation due
to the use of bad quality groundwater in the brackish areas of Rechna Doab, the
government should put a ban on the installation of new tubewells in the areas
where the hazard of up-coning of brackish water is high and must reallocate
surface water to these areas.

In
the past, government invested on large-scale drainage tubewell network to manage
the salinity and waterlogging on the farms in the Rechna Doab. Currently,
besides giving a subsidy on the new private tubewells the government is also
encouraging communities to install community tubewells in the areas where the
groundwater is of better quality. It is also necessary to formulate some legal
framework to regulate tubewell operations in areas where the recharge problem
exists. The existing institutions like the On Farm Water Management (OFWM)
program and Punjab Groundwater Sector Development Program (PGSDP) may be
strengthened to monitor aquifer depletion/recharge on a regular basis to ensure
the sustainable supplies of groundwater in the fresh groundwater areas.

References

Bredehoeft,
J.D. and R.A.Young, (1983). Conjunctive Use of Groundwater and Surface Water for
Irrigated Agriculture: Risk Aversion. Water
Resource Research, 19(5): 1111-1121.

Chaudhry,
A. and Shah, F. (2003). Conjunctive use of surface and groundwater resources
under alternative institutional mechanisms. Department of Agriculture and
Resource Economics, University of Connecticut, Storrs, USA.

Meyer.W.S,
Godwin,D.C, and White,R (1996). SWAGMAN Destiny: A tool to project productivity
change due to salinity , water logging and irrigation management. Proceedings of
the 8th Australian Agronomy Conference, Toowoomba, 1996.